As an example, the "file_uploads" configuration option defines whether or not file uploads are allowed. This is a PHP_INI_SYSTEM option and if you attempt to set it in an .htaccess file as shown below then it will be ignored and the original value retained:

php_value file_uploads 1

When setting PHP_INI_SYSTEM options the "php_value" must be instead written as "php_admin_value". An example virtualhost might look like this:

This would then prevent file uploads for this particular virtualhost, and all the others would use the setting from the php.ini file, unless also defined like above.

Note that if you added the following to an .htaccess file you will get an internal server error message:

php_admin_value file_uploads 1

because only php_value directives can be included in .htaccess files.

There are also php_flag and php_admin_flag which can be used for settings which only have on and off (true/false, 1/0) settings but as shown above you can use php_value and php_admin_value for all settings including the flags.